Deniquelata Ariyawansa & K.D. Hyde, 2013

Ariyawansa, Hiran A., Maharachchikumbura, Sajeewa S. N., Chukeatirote, Samantha C. Karunarathne Ekachai, Bahkali, Ali H., Kang, Ji-Chuan, Bhat, Jayarama D. & Hyde, Kevin D., 2013, Deniquelata barringtoniae gen. et sp. nov., associated with leaf spots of Barringtonia asiatica, Phytotaxa 105 (1), pp. 11-20 : 13-16

Deniquelata Ariyawansa & K.D. Hyde , gen. nov.

MycoBank MB 800703

Etymology: The generic epithet is from the combination of two Latin words denique and lata, meaning short and broad, in reference to the asci having a short, broad pedicel.

Habit parasitic on living leaves. Ascomata immersed, solitary, scattered, globose to subglobose, dark brown to black, smooth-walled, with a distinct ostiole, apex somewhat papillate to depressed. Peridium several-layered, outer wall composed of small, dark brown to black, heavily pigmented, thick-walled, comprising cells of textura angularis and fusing with the host, inner wall consist with broad yellowish brown cells, inwardly lined by hamathecial tissues. Hamathecium of dense with pseudoparaphyses. Pseudoparaphyses broad, hyaline, embedded in a gelatinous matrix. Asci 8-spored, bitunicate, fissitunicate, clavate to broadly-clavate, with a short, broad, furcate pedicel, rounded at apex and with an ocular chamber. Ascospores biseriate, partially overlapping, oblong to narrowly oblong, reddish brown to dark yellowish brown, muriform, with three transverse septa and 1-2 vertical septa in the central cells when mature, constricted at the septa, verruculose, without a sheath. Generic type:

Deniquelata barringtoniae Ariyawansa & K.D. Hyde , sp. nov. FIGS. 1A–F, 3G–S

MycoBank MB 800704

Etymology: The specific epithet barringtoniae is based on the host genus from which the fungus was isolated. Habit pathogenic, causing large brown spots on living leaves of Barringtonia asiatica ( FIG. 2A− E ). Ascomata 150−180 µ m high, 164−190 µ m wide (x = 175 × 167 µ m, n = 10), immersed, scattered, globose to subglobose, black to dark brown, smooth walled, with a papillate to depressed elongate ostiole ( FIG. 3A,B ) Peridium 9−17 µm diam (x = 12, n = 10), composed of 3−5 layers of brown to black, darkly pigmented, small, thick-walled, 2−5 µm wide cells of textura angularis, with outer wall fused with the host cells, inner wall consists of 2 layers of polygonal to rectangular, light brown-hyaline cells 1–4 µm diam. ( FIG. 3C ). Hamathecium composed of dense, 1−3 µm diam (x = 2, n = 20), broad, hyaline, septate pseudoparaphyses, surrounding the numerous asci and embedded in a gelatinous matrix ( FIG. 3D ). Asci (60−)68−80 × 1015 µm (x = 72 × 13 µm, n = 20), 8-spored, bitunicate, fissitunicate, clavate to broadly-clavate, with a 9–17 µm, short, broad, furcate, long pedicel, rounded at apex, ocular chamber up to 1−2 µm wide, 1−3 µm high ( FIG. 3E− G ). Ascospores 14−16 × 5−7 µm diam (x = 15 × 6 µm, n = 40), biseriate or distichously arranged, partially overlapping, oblong to narrowly oblong, straight or somewhat curved, reddish-brown, with three transverse septa and 1−2 vertical septa in the central cells, constricted at the primary and secondary septa at maturity, verruculose, straight or slightly inequilateral, without a gelatinous sheath ( FIG. 3H− J ).

Cultural characteristics: Ascospores germinated on WA within 18 h and germ tubes were produced from each cell ( FIG. 3K ). Colonies grew slowly on MEA, attaining 3 mm diam. After 14 days at 27°C, effuse, velvety, entire to slightly undulated at the edge and remaining white to pinkish white ( FIG. 3L− S ). After 6 months of incubation, the colonies on malt extract agar and water agar media co ntained only superficial, branched, septate, smooth, mycelia with no asexual-stage.

Material examined: THAILAND, Chiang Rai Prov., Muang District, Bandu, Baan Khuakhae, 31 M. 17 on leaf of Barringtonia asiatica (Lecythidaceae) 18 September 2011, K.D Hyde, RP0025 ( MFLU 12-0303; holotype)—extype living culture ( MFLUCC 110422); Chiang Rai Prov., Muang District, Bandu, Baan Khuakhae, 31 M. 17, on leaves of Barringtonia asiatica (Lecythidaceae) , 15 May 2012, H. A Ariyawansa, RP0025 ( MFLU 12-0304, paratype)—extype living culture ( MFLUCC 120257).

Distribution: On living leaves of Barringtonia asiatica Thailand.

Pathogenicity test ( FIG. 4 ): Leaves wounded by pinpricking inoculation technique, initially developed small, circular, ash-coloured spots which subsequently transformed into brown spots. After 10 days of incubation, the spots expanded to 2 mm diam. The spots further enlarged and became sunken causing soft decay of the leaf tissues, surrounded by white mycelium. The pathogen, re-isolated from the leaf spots was found to be identical with the original strain and thus confirmed its pathogenicity. No symptoms were observed on leaves inoculated by agar plugs with fungal mycelium but without wounding and also in the case of controls. The experiment was carried out using four replicates and repeated three times. In all cases, the results were similar.

Figures

FIGURE 2. Habit of Deniquelata barringtonia. A–E. Leaves with characteristic leaf spots (Holotype). F. Immersed ascomata on leaf tissue.

FIGURE 3. Deniquelata barringtoniae (holotype). A–B. Section of ascoma (TS). C. Section of peridium comprising a few layers of cells. D. Hyaline, pseudoparaphyses E–G. Eight-spored asci with short, broad pedicel at the base. H–I. Reddish-brown, muriform, ascospores. J. Ascospores stained in Indian Ink K. Germ tubes developing from ascospore cells L–M. Surface and lower view of colonies on MEA. Scale bars: C–D = 100 µm, E = 10 µm, F = 10 µm, G = 30 µm, H–I = 10 µm, J–L = 30 µm, M-P = 10 µm, Q= 20 µm.

FIGURE 4. Symptoms appearing on pin pricked leaves of D. barringtonia inoculated with agar plugs.